Analysis of a limb-specific regulatory element in the promoter of the link protein gene
Supplemental to figure 1 of "Analysis of a limb-specific regulatory element in the promoter of the link protein gene." This supplemented figure 1 shows the details of the X-gal staining from embryos containing the -1020 and -690 nt Hapln-lacZ transgenes. Fig. 1. Link protein gene promoter constructs show in vivo expression patterns in either the skeleton or limb/genitalia. (A) Two different link protein promoter fragments consisting of the −1020 and −690 nt regions were tested in transgenic mice. (B) A representative E15.5 mouse transiently expressing the −1020 promoter region showed only X-gal staining in appendicular and axial cartilaginous skeletal tissues. A dark background was used to provide contrast to the photograph to allow easy visualization of the discrete expression in cartilage sites. (B-1) Sectioning showing staining in the tibia after X-gal and eosin counter-staining. (B-2) Immunofluorescence using antibody to Hapln1. (C) and (D) The shorter −690 promoter region demonstrated high-level expression in the limb and genitalia as shown in two representative mouse embryos. As shown, embryos showed variability of X-gal staining in the limb and hind paw regions. The embryos in C and D were dissected and either the paws (C1, D1; 5x) or genital tubercle (C2, D-2;20x) were examined by tissue-sectioning and counter-staining with eosin. In paws and genitalia mesenchymal cells show X-gal staining underneath the un-stained epithelial cells.